1. Field of the Invention
The present invention generally relates to hypodermic syringes and accompanying needles for injecting substances into--or withdrawing fluids from--a human being or an animal. More particularly, the invention relates to a safety device for embedding the tip of a syringe needle into embeddable matter in order to prevent accidental needle stick injury.
2. Description of the Prior Art
More than ever before considerable operator risk is associated with the use of hypodermic syringes and accompanying needles for injecting substances into donees or withdrawing fluids from donors. For when a syringe and needle are exposed to a virulent contagion, life threatening disease may be transmitted from the donor or donee to the operator of the syringe. In order to minimize accidental transmission of such contagion, current medical practice prescribes that hypodermic syringes and needles be discarded after one-time use. Additionally, prior to discard, current medical practice prescribes that the sharp end of needles be embedded in an embeddable substance to prevent accidental needle stick injury. This is usually accomplished by the operator pushing the needle of the hypodermic syringe held in one hand into a cork, rubber stopper, or the like held in the other hand. Once the tip of the needle is embedded, the operator and all others are protected from accidental needle stick. However, in any attempt to embed the tip of a needle into embeddable matter, operator error may cause a needle to puncture the skin of the operator.
Alternative devices for embedding, sealing, guarding, protecting, shielding, or enclosing needles of hypodermic syringes, whose purpose is to prevent needle stick injury and contamination of samples of body fluids, have been devised. Representative of the prior art are the hypodermic syringe arrangements disclosed in U.S. Pat. Nos. 4,795,443 (Permenter et al), 4,747,836 (Luther), 4,655,751 (Harbaugh), 4,573,976 (Sampson et al), 4,425,120 (Sampson et al), 3,658,061 (Hall), 2,854,976 (Heydrich), and 1,921,034 (Marche).
U.S. Pat. No. 4,795,443 discloses a needle of hypodermic syringe sealing device with a cap that can be slid forwardly past the tip of the needle and then rearwardly so that the end of the needle becomes sealed in the cap.
U.S. Pat. Nos. 4,747,836 and 3,658,061 disclose a needle of hypodermic syringe guarding devices with slotted cylinders which, before use, are rotated away from the needle and which, after use, are rotated back to once again enclose the needle.
U.S. Pat. Nos. 4,665,751 and 2,845,976 respectively disclose a needle of hypodermic syringe protecting devices with a cylindrical shell slidable between a needle exposing position and a needle covering position or a cylindrical shell removable for a needle exposing position and engageable for a needle covering position.
U.S. Pat. Nos. 4,573,976 and 4,425,120 disclose a needle of hypodermic syringe shielding devices with a guard movable between an extended needle-shielding position and a retracted needle-nonshielding position.
U.S. Pat. No. 1,921,034 discloses an enclosing device for a hypodermic syringe and needle sealable within an enclosure in a carrying position and advanceable to an exposing position where the needle projects beyond the end of the enclosure.
While many of the structural arrangements of improved hypodermic syringes for preventing air contamination of samples of body fluids and accidental needle stick injury appear to function reasonably well and generally achieve their objectives, most seem to embody shortcomings which make them less than optimum design. For instance, many do not provide positive means for embedding the tip of the needle into embeddable matter or positive means for retaining the embedded needle in embeddable matter. Consequently, a need still exists for a different approach in the design of an improved hypodermic syringe. It is to the provision of such that the present invention is primarily directed.